Concrete mixer



May 23g 1939. 5, M SKRZYNSKI 2,159,184

- CONCRETE MIXER Filed Dec. v16, 1937 I INVENTOR ATTORNEY S Patented May23, 1939 UNITED STATES PATENT OFFICE CONCRETE MIXER Application December16, 1937, Serial No. 180,068

2 Claims.

This invention relates to concrete mixers and more particularly to suchmixers in which the mixing is accomplished in a rotary mixing drum.

Itis an object of the invention to provide improved water supply meansfor a concrete mixer, achieving certainty in measurement and at the sametime reducing the need for cleaning and facilitating cleaning whennecessary.

It is a further object of the invention to provide a constructionadapted to cramped installations, such as those mounted on trucks formixing in transit.

With these and other objects not specifically referred to in view, theinvention consists in certain novel parts, arrangements and combinationswhich will be described in connection with the accompanying drawing andthe novel features pointed out in the claims hereunto annexed.

A preferred construction for effecting the objects of the invention isshown in the accompanying drawing, in which- Figure 1 is a sideelevation of a truck with a mixing unit mounted thereon;

Figure 2 is a fragmentary side elevation of the mixing unit of Figure 1,on an enlarged scale and with part of the casing broken away to revealinternal features of construction;

Figure 3 is an end view of the mixing unit looking to the right ofFigure 1;

Figure 4 is a cross-section on an enlarged scale taken on the line 4 4of Figure 2;

Figure 5 is a perspective View of a scraping blade hereinafterdescribed;

Figure 6 is an exploded perspective View showing the relation of theblade of Figure 5 to other parts of the apparatus unassembled;

Figure 7 is an enlarged view of part of Figure 2; and

Figure 8 is a view partly broken away of a portion of Figure 7.

Referring now to the drawing, the apparatus is generally of a familiartype illustrated, for example, in Jaeger Patent No. 1,948,715,consisting of a motor truck I upon which is mounted the mixing unit 2,comprising a rotatable mixing drum 3 and a relatively stationary watersupply tank 4.

The drum 3 is supported at its discharge or rear end by rollers 5(Figure 3) on the truck engaging a cylindrical track 6 on the drum andat the front end by a roller bearing 'l (Figure 4). Means for rotatingdrum 3 is provided and comprises a motor 8 with gear box 9, shaft IIJand pinion ll on the truck engaging a gear Wheel I2 on the drum (Figure3), the usual clutch and gear shift levers I3, Ill, being provided fordisconnecting the drive or for driving in either direction.

The invention is particularly useful in truck mounted installationsprovided with separate 5 drive for the drum, due to space limitations,but it is not restricted to such installations, being applicable also tothe well known types of apparatus in which the truck engine itselfdrives the drum or in which the unit is not truck mounted. 10

The drum is provided with the usual inlet port for dry materials, suchas cement, sand, gravel, stone and the like, which is closed duringoperation by cover l5, and is also provided with the usual dischargeport I 5 which during operation 15 is opened and closed by a hand WheelIl.

Internally the drum carries helicoidal mixing blades i8 and a Water pipeI9 fixed to it by struts 28 on the drum. Outlets 2l from pipe I9 furnishwater to the interior of the drum and are shown 20 as guarded by a bell22. A bracket 23 within bell 22 carries an annular rubber flap 2li atthe open end of the bell which closes the outlets 2| against ingress ofthe drums solid materials. Water emitted from outlets 2l forces flap 24open 25 and passes into the drum between the inner edge of the flap andpipe I9 and also between the outer edge of the ap and bell 22. When nowater is flowing through outlets 2| the flap 24 serves the purpose ofpreventing or retarding passage of 30 solid materials into and cloggingpipe le.

Water tank l is supported by brackets 25 from a bearing post 2S and isgenerally cylindrical in shape except for a rectangular offset portion2'! (Figure 3). It is provided with the usual filling 35 cap 23 andgauge glass 29, the latter being calibrated, usually in gallons,although it may be calibrated in gravimetric rather than volumetricunits where local regulations or particular speciflcations require it.Leading from oset 2l is an outlet nipple 3i? which communicates, througha T 3 I, a gate valve 32, a hose 33 and a pipe 34 with water pipe I 9and its outlets 2i. Gate valve 32 is of the type known as quick acting,being provided With a readilly accessible handle 35, depressing orraising of which through an arc of approximately serves to close or openthe valve completely. The forward branch of T SI is provided with aclosure member such as plug 35 which may be unscrewed for inspection or50 cleaning of the water line into the drum.

Fixed to pipe 3ft, as by welding, is a bracket 31 by means of which thispipe is secured to bearing l. One of the cap screws customarily used tofasten the face plate 33 of the bearing may, as 55 shown, be used toattach this bracket to the bearing.

A stuiiing box 39 is employed as a trunnion or journal for the drum 3and is fastened thereto by an integral flange 40 and rivets 4I.Internally, stung box 39 has a smooth cylindrical bore 42 tting quiteclosely, but not necessarily Watertight, the forward end of pipe I9 andthe rearward end of stationary pipe 34 as shown best in Figure '7, thesetwo pipes being separated a. small distance, which may be of the orderof a quarter inch. The forward end of stuffing box 39 is pro-vided withsubstantially water tight packing 43, relative rotation between thestufling box 39 and its packing 43 on the one hand and stationary pipe34 on the other being permitted.

A cleaning and agitating device 44 is provided and advantageously takesthe form of a tapered cylindrical blade 45 formed integral with a splitcollar 46, the latter having a driven t with pipe I9 as shown best inFigures 4, 7 and 8, and the former extending into pipe 34 substantiallyits length and being in close contact with its inner surface. Aconvenient method of manufacture of this part 44 is to cut it out of asection of tubing or pipe or a flat piece of metal bent into a splittube, in which case suitable steel may be employed to secure durabilityand resistance to pounding of the split collar 46 and blade 45 may betempered Vfor hardness and stiffness. A1- ternatively, member 44 may bemade of a solid pipe section and undercut or relieved, as necessary, toenter pipe I9 with a close fit. Such method of manufacture, while notquite as simple, results in a member inherently of somewhat greaterstrength. As pipe I9 is aiiixed to drum 3, and hence rotates therewith,and pipe 34 is stationary, rotation of drum 3 results in rotation ofblade 45 within pipe 34, continuously scraping the inner surface of thelatter and agitating any solid materials which may be within it.

In the usual operation of the apparatus drum 3 is filled with drymaterials through the :inlet port, normally closed by cover I5, and isrotated suiciently to mix these materials in a dry state as much as maybe desirable, during which time handle 35 will be depressed and gatevalve 32 closed. Tank 4 will normally be substantially filled so thatgauge glass 29 gives a Zero reading. When water is to be introduced intothe drum the operator opens valve 32 by lifting handle 35 and watchesthe gauge glass until the required amount of water has run out asindicated thereby, whereupon` handle 35 is quickly depressed, closingvalve 32. After introduction of the water, the rotation of drum 3 iscontinued as long as may be necessary to achieve thorough mixing.

As best shown in Figures 2, 3 and 7, T 3I,valve 32, hose 33 and pipe 34are substantially in line. In consequence, it is necessary only toremove plug 36 and open valve 32 to have a substantially unobstructedview of the water line for inspection and a clear passage for theinsertion of cleaning implements. Hose 33 may advantageously be given aslight downward inclination, as shown, without seriously interferingwith inspection or cleaning, and this inclination has a tendency toprevent solid materials remaining in the hose and setting. -Setting ofsolid materials in pip-e 34 is prevented by blade 45, previouslyreferred to.

As suggested above, no device such as the rubber flap 24, previouslyreferred to, can absolutely prevent the passage of solid matter backinto the water supply, and this is particularly true when such a devicehas been in use and has become worn. For this reason it is found inpractice that solid material often will travel back through the watersupply system so far as this is open and in a case where the supply ofwater is regulated by a standpipe or the like in the tank, rather thanby a valve, the solid material may be found even in the tank itself. Asa result, experience has shown that a mixer unit without theimprovements of the present invention may, in addition to requiringfrequent cleaning, require a long time for each cleaning, ranging up toan hour or two, or even longer. With the present invention the onlyparts which require cleaning are those located rearwardly of the gatevalve 32 and these are readily inspected by removing the plug 35 and maybe cleaned through this opening, or, if required, by disconnecting hose33. Setting of solid material in the hose 33 is impeded by the slightinclination of this member, by the rotary movement imparted to waterwithin pipe 34 by the blade 45, and by the flexible nature ofthe hoseand the vibration imparted thereto by the rotation of the mixing drinn.In any event, this member is easily cleaned because of its vexiblenature.

What is claimed is:

l. In a rotary concrete mixer, and in combination, a rotatable mixingdrum, means for rotating said drum, means for introducing water axiallyof said drum, including a pipe stationary relative to said drum, and asecond pipe located axially of said drum, fixed thereto for rotationtherewith and adapted to discharge water into the interior thereof, saidpipes being disposed in axial alignment with ends adjacent, and` meansforY preventing setting of concrete materials in the iirst mentionedpipe, comprising a blade affixed tov said second pipe for rotationtherewith and extending into said first mentioned pipe.

2. In a rotary concrete mixer, and in combination, a rotatable mixingdrum, means for rotating said drum, means for introducing water intosaid drum, comprising a forward pipe section, a rearward pipe sectionand a gate valve located therebetween, said pipe sections and gate valvebeing substantially axially aligned, and said forward pipe section beingprovided with a removable forward closure member, whereby when said gatevalve is open and said closure member removed, said means forintroducing water form a substantially cylindrical open passage, and acleaning member attached to said drum for rotation therewith andextending forwardly into said rearward pipe section,

